Solid-State Phase Transformation in Cubic Silicon Carbide

The thermal stability of single crystalline 3C-SiC was investigated at temperatures from 1800 to 2400°C in an Ar atmosphere, and a solid-state phase transformation from 3C-SiC to 6H-SiC was observed above 2150°C. Single crystals of 3C-SiC(100) grown on Si(100) were used as starting crystals after removing Si. Annealings were carried out with changing temperature, pressure and time. The change in the Si/C composition ratio of annealed samples was determined by Auger electron analysis. The polytypes of samples were examined by photoluminescence, Raman scattering, X-ray diffraction and reflection high-energy electron diffraction before and after annealing. The spatial distribution and depth profile of the phase-transformed 6H-SiC region in annealed samples were observed by means of Raman microscopy. The mechanism of 3C→6H phase transformation in SiC is discussed.